If the range that has the constants is multi-area, then this gives xl2002
problems (xl2k and up, IIRC, ok in xl97).
I think I'd go through each area:
Option Explicit
Sub testme01()
Dim myArea As Range
Dim myRng As Range
With ActiveSheet
Set myRng = Nothing
On Error Resume Next
Set myRng = .UsedRange.SpecialCells(xlCellTypeConstants)
On Error GoTo 0
If myRng Is Nothing Then
MsgBox "no constants"
Else
For Each myArea In myRng.Areas
With myArea
.Value = Application.Proper(.Value)
End With
Next myArea
End If
End With
End Sub